Tens of thousands of European travellers have been stranded in rail stations, traffic jams and airports as heavy snow and ice continues to cause massive disruptions at the start of the Christmas holiday season.

A deadly blizzard has also blanketed much of the eastern United States, cutting power to tens of thousands of homes, paralysing air traffic and stranding many motorists amid the worst storms to hit the region in decades.

In Poland, at least 15 people have died of exposure, mainly the homeless or careless drunks caught outside in temperatures that plunged to minus 20 degrees Celsius, according to police.

Another homeless Pole froze to death while sheltering in a doorway in the French Mediterranean port of Marseille, and a Frenchman was found dead in his ice-cold caravan near the northern town of Arras.

In Germany, a 46-year-old homeless man froze to death overnight in the southwestern city of Mannheim while sleeping on a bare pavement, while temperatures in Bavaria plunged to a glacial -33.6C.

Two more Germans died in road accidents caused by the icy conditions.

Forecasters across the continent are expecting more snow and freezing rain over the next couple of days, but with temperatures rising slightly and the outlook gradually improving.

Roads and railways have been closed or disrupted by snow drifts, black ice or floods across northern and western Europe, from Portugal to the Netherlands, and flights from London, Brussels and Paris airports were delayed.

The most crippling problems hit cross-Channel transport between Britain and France, amid chaotic scenes after the Eurostar passenger service from London to Paris was shut down for a second day after at least five breakdowns.

Eurostar, the operator of the Channel Tunnel passenger trains, admitted it could not say when services would resume, with more than 24,000 passengers attempting to travel ahead of Christmas already affected.

The company said it would send test trains along the route to see if they could withstand the sub-zero temperatures in northern France which are believed to have caused trains to break down in the tunnel on Friday (local time).

"We did run two or three trains yesterday. They all got through the tunnel OK, but one or two of them showed symptoms of the problem that happened on Friday night," Eurostar director Richard Brown said.

"We will not start services again until we're sure that we can get them through safely."

More than 2,000 passengers spent Friday night trapped in the undersea tunnel, some without anything to eat or drink. There were reports of heated rows and some passengers bitterly criticised the company.

Approach roads to the ports of Dover and Calais were snarled by tail-backs because of heavy snow and queues of trucks waiting for delayed shuttle trains through the Channel Tunnel.

At Paris Charles de Gaulle, 40 per cent of flights have been cancelled and the remaining services were leaving an average of one hour late, while the city's second airport, Orly, was the scene of a strike by security staff.

Deadly blizzards

In the United States, the governors of Virginia, Maryland, West Virginia and Delaware have declared states of emergency following the snowstorms.

Three people have died on Virginia roads, with around 3,000 accidents forcing the closure of Virginia interstates for several hours.

Officials reported many drivers and passengers had been stranded in their vehicles, some for more than 12 hours.

Emergency services delivered heated meals and 400 bottles of water for stranded motorists, while others were moved to shelters.

In the bull's eye of the weather, Washington shattered a 1932 December snowfall record, with 40 centimetres covering streets and homes.

And with more snow forecast to fall on the US capital in coming days, the snowstorm is on track to become one of the biggest to hit the city since records began in 1885.

The massive storm at one point stretched 800 kilometres across a dozen states, affecting around a quarter of the US population.

President Barack Obama, after attending the climate change summit in Copenhagen, raced home to avoid the worst of the storm that hammered the East Coast with more than 61cm of snow in some places.

He got back before dawn on Saturday, two days before winter's official arrival. By Saturday afternoon, the capital region's three main airports - Reagan National, Washington Dulles International and Baltimore Washington International - had cancelled all incoming and outgoing flights, stranding thousands of passengers.

It was bleak news for millions hoping to drive or fly ahead of Christmas on one of the busiest travel weekends of the year.

With near white-out conditions forcing many residents to stay home and shopping malls shuttered or closing early, the extreme conditions also looked likely to take a bite out of retail sales.

The major shopping day usually accounts for some $US15 billion of all nationwide sales on the last weekend before Christmas.